In overhead conveyors, trolleys of hoists run on rails that are suspended from the ceiling. Continuous rails can be used for short distances. For longer distances, the rails must be divided for assembly and production-related reasons. Thus, the problem arises of connecting the individual rail sections at the joints so that the traveling trolley moves in jerk-free fashion across the rail joint.
Furthermore, the joint connector arrangement that bridges the rail joint must also transmit bending forces/torques introduced by the trolley traveling gear into the rail on one side of the joint to the other rail across the rail joint. Otherwise, a significant height offset would occur in the area of the rail joint. A lateral offset of the rails is also undesired because side guide wheels of the traveling gear could catch on these parts, or could bump against the resulting step.
The running rails of overhead conveyors typically have a somewhat I-shaped cross-sectional profile, wherein the upper and lower flanges usually have a hollow profile for weight and stability reasons. No connection devices could be mounted on the web connecting the two flanges, as the web is often used as a substructure for conductor lines.
A rail joint connector arrangement for overhead conveyors is known from DE 34 01 183 A1. Here, the running rails are assembled from two roll-formed halves, wherein the joint between the two rail parts runs through the center of the web. Thus, each half of the running rail carries one half of the upper flange and one half of the lower flange. In the area of the upper flange, there remains a continuous gap, while in the area of the lower flange, the halves are curled inward.
In the upper flange, there is a joint connector arrangement made from two abutment pieces screwed together by means of a tensioning bolt. In the lower flange, there are brackets seated in each chamber formed by the rolled profile that bridge the joint and are fixed in the chamber on either side of the joint by means of screws used as alignment pins. A disadvantage in this construction is that no biasing forces could be generated in the lower flange transverse to the separation plane of the joint.
At the upper flange, the abutment pieces in this location do not allow sufficient lateral centering. Centering by the tensioning bolt is usually not sufficient. In the area of the upper flange, this is relatively non-critical since the wheels of the trolley traveling winch do not run over this flange. The use of such a construction in the area of the lower flange would be inadequate since the centering or correctly positioned fixing of the two rail ends at the joint is not adequately assured.